1. Field of the Invention
The present invention relates to a method of manufacturing a toner.
2. Discussion of the Background
In recent years, demand for quality images from the market has spurred development of suitable electrophotographic apparatuses and developing agents including toner for use therein. Toner capable of producing quality images is required to have a sharp particle size distribution. Toner particles of toner having a sharp particle size distribution behave in keeping with each other during development, which improves minute dot reproducibility.
Therefore, toner (chemical toner) has been developed based on a suspension polymerization method or an emulsification polymerization agglomeration method in which toner particles are granulated in an aqueous phase to achieve the goal described above.
In the suspension polymerization method, toner particles are prepared from oil droplets formed by adding and stirring a monomer, a polymerization initiator, a coloring agent, a releasing agent, etc. in an aqueous phase containing a dispersion stabilizer followed by polymerization reaction by heating. Toner particles can be reduced in size by the suspension polymerization method. However, a dispersion stabilizer is required which may degrade the chargeability when remaining in toner. Without a dispersion stabilizer, a releasing agent tends to be present in the inside of an oil droplet when the oil droplet is formed so that the releasing agent cannot suitably exist on the surface of obtained toner particles.
In addition, unexamined published Japanese patent application No. (hereinafter referred to as JOP) 2004-226669 describes a method in which a releasing agent particulate covered or impregnated with a vinyl polymer by adding a polymerizable vinyl monomer and a water-soluble polymerization initiator to a releasing agent emulsion for polymerization is added when a toner component is emulsified so that a particulate releasing agent is uniformly and firmly attached to the surface of toner. However, polymerization of a releasing agent emulsion and a polymerizable vinyl monomer is required in this method. Also, the glass transition temperature (Tg) of the resin forming the particulate releasing agent is high, which degrades the releasing property at a low temperature and the low temperature fixing property.
In addition, Japanese patent No. 2663016 describes a method in which a toner is manufactured by suspension-polymerization of a material having a polar group and a polymerizable monomer containing a releasing agent in an aqueous medium so that the toner can contain a wax having a low melting point not suitably used for a toner manufactured by a pulverization method. A non-polar component such as wax is not present close to the surface of toner particles contrary to the polar component so that the toner has a pseudo-capsule structure in which the surface of the toner is covered with the polar component. However, the distribution of the wax inside the toner particle is not analyzed and thus unknown.
JOP 2002-6541 describes a toner containing a wax encapsulated therein and locally present on the surface of the toner. However, the detail of the dispersion state near the surface of the toner is not described.
JOP 2004-246345 describes the ratio of a wax exposed to the surface of a toner which is measured and determined by Fourier transform infrared attenuated total reflection (FTIR-ATR). However, toner blocking and hot-offset, and filming and paper winding are completely in a trade-off relationship. Therefore, it is difficult to improve the fixing property furthermore by improvement of toner or control of the average dispersion diameter of wax.